@article {333814, title = {Insights into hominin body size, locomotion, and behavior from Early Pleistocene trackways in northern Kenya}, journal = {Proceedings of the National Academy of Sciences}, volume = {123}, year = {2026}, month = {2026/07/27}, abstract = {

The Early Pleistocene fossils of the Koobi Fora Formation, northern Kenya, record two well-documented hominin genera,\ Homo\ and\ Paranthropus, preserved in the same deposits. Evidence for their ecological sympatry consists of co-occurring footprints of diverse morphologies, suggesting that\ Homo erectus\ and\ Paranthropus boisei\ were present in the same lake margin habitats over hundreds of thousands of years. Here, we report on a ~1.43 Ma fossil footprint assemblage that sheds light on Early Pleistocene hominin paleobiology and behavior. The internal morphologies of the hominin tracks align with others previously attributed to\ P. boisei, indicating patterns of foot morphology and locomotion different from modern\ Homo\ and more consistent with those seen in earlier\ Australopithecus\ species. However, the tracks indicate body sizes that exceed the largest skeletal estimates for\ P. boisei, raising the possibility that they may belong to\ H. erectus. Depending on their attribution, the tracks demonstrate a) larger body sizes and greater size variation in\ P. boisei\ than previously recognized, or b) levels of intraspecific anatomical and locomotor variation in\ H. erectus\ that far exceed those yet observed in modern humans or other fossil taxa. Regardless of their attribution, these tracks indicate larger than average body sizes. This supports the hypothesis that they capture a group that included multiple adult males and offers rare direct evidence for hominin social behavior. The ecological context of the tracks suggests that hominins were accessing resources in a deltaic lake margin habitat.

}, isbn = {0027-84241091-6490}, doi = {http://dx.doi.org/10.1073/pnas.2530996123}, url = {https://www.pnas.org/doi/10.1073/pnas.2530996123}, author = {Hatala, Kevin G. and Roach, Neil T. and Harris, John W. K. and Kiura, Purity and Ndiema, Emmanuel K. and Sila, Ben and Kipkebut, David and Waweru, Joyce and Kisale, Philiphine and Longaye, Apolo Alkoro and Sale, Hilary and Behrensmeyer, Anna K.} }